code: def testEmpty(self):
      self.assertComputeFails(FlatnessSFX(), [])
  
file_path: essentia/test/src/unittests/sfx/test_flatnesssfx.py
imports: from essentia_test import *
  import numpy
label_desc: Use image node_id 1 for calling the TestFlatnessSfx obj's underlying member method code with example usage: obj.testEmpty() without return types